(1) Field of the Invention
The present invention relates to a trailing edge cooling design for an airfoil portion of a turbine engine component.
(2) Prior Art
FIG. 1 illustrates a conventional turbine blade 10 having a single cutback trailing edge. As can be seen from FIG. 1, the airfoil portion 12 of the blade 10 has a cooling scheme which attempts to cool the very trailing edge 14 as well as the aft pressure side of the airfoil portion 12 with the same set of cast features. That is, the cooling air passes through a first row of cross-over holes 18 and a second row of cross-over holes 20 and finally into the cut back slot 23. The cavity 22 between the rows 18 and 20 of cross-over holes is also a source of cooling air for the pressure side of the airfoil portion 12 via one or more rows of cooling film holes 24. The cooling air flowing from the film holes 24 is used to cool the pressure side slot lip 16. The cavity 22 is a difficult area in which to predict internal pressures. It is sensitive to cross-over geometry and the drilling tolerances of the holes 24. Balancing the flow between cooling the very trailing edge 14 of the airfoil portion 12 and the pressure side lip 16 can be very difficult, given the existence of small aerodynamic wedge angles, and the casting tolerances on the cross-over holes 18 and 20.
FIG. 2 illustrates another airfoil portion 12′ of a turbine engine blade 10′ having a single cutback trailing edge. In this type of turbine engine blade, there are cooling air supply cavities 30 and 32. A plurality of supply cavities 34 are formed in the walls of the airfoil portion 12′. Each supply cavity 34 receives cooling fluid from the root of the airfoil and/or from one of the supply cavities 30 and 32. At least some of the supply cavities 34 cooperate with a series of film cooling holes 36 to create a film of cooling fluid over one of the pressure side 38 and the suction side 40 of the airfoil portion 12′. To cool the trailing edge 14′, a trailing edge cutback slot 42 is formed in the airfoil portion 12′. The cutback slot 42 receives cooling fluid from a cavity 44.